Alkanolamine semiconductor process residue removal composition and process

ABSTRACT

A two carbon atom linkage alkanolamine compound composition comprises the two carbon atom linkage alkanolamine compound, gallic acid or catechol, and optionally, an aqueous hydroxylamine solution. The balance of the composition is made up of water, preferably high purity deionized water, or another suitable polar solvent. A process for removing photoresist or other residue from a substrate, such as an integrated circuit semiconductor wafer including titanium metallurgy, comprises contacting the substrate with the composition for a time and at a temperature sufficient to remove the photoresist or other residue from the substrate. Use of the two carbon atom linkage alkanolamine compound in the composition and process provides superior residue removal without attacking titanium or other metallurgy, oxide or nitride layers on the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/628,060, filed Apr. 17, 1996, which is in turn a continuation-in-partof application Ser. No. 08/078,657, filed Jun. 21, 1993, now abandoned,which is in turn a continuation-in-part of application Ser. No.07/911,102, filed Jul. 9, 1992, now U.S. Pat. No. 5,334,332, which was acontinuation-in-part of application Ser. No. 07/610,044, filed Nov. 5,1990, now U.S. Pat. No. 5,279,771. It is further a continuation-in-partof application Ser. No. 08/523,889, filed Sep. 6, 1995, which is in turna continuation of application Ser. No. 08/273,143, filed Jul. 14, 1995now U.S. Pat. No. 5,482,566, which is in turn a division of applicationSer. No. 07/911,102, filed Jul. 9, 1992 now U.S. Pat. 5,334,332. Thedisclosures of those applications are hereby incorporated by referencein this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a cleaning composition andprocess for removal of organic, organometallic and metal oxide residuesfrom substrates. More particularly, it relates to such a composition andprocess for removing semiconductor device fabrication residues fromsemiconductor device substrates, such as etching residues after plasmaetching processes in the fabrication of integrated circuits on siliconwafers and similar processes. Most especially, it relates to such acomposition and process which is effective for the removal of thesematerials while avoiding substantial attack on metal or insulationlayers employed in integrated circuits, including titanium layers.

2. Description of the Prior Art

As integrated circuit manufacturing has become more complex and thedimensions of circuit elements fabricated on silicon or othersemiconductor wafers have become smaller, continued improvement intechniques used to remove residues formed from such materials has beenrequired. Oxygen plasma oxidation is often used for removal ofphotoresist or other polymeric materials after their use during thefabrication process has been completed. Such high energy processestypically result in the formation of organometallic and other residueson sidewalls of the structures being formed in the fabrication process.

A variety of metal and other layers are commonly employed in integratedcircuit fabrication, including aluminum, aluminum/silicon/copper,titanium, titanium nitride, titanium/tungsten, tungsten, silicon oxide,polysilicon crystal, and the like. The use of such different layersresults in the formation of different organometallic residues in thehigh energy processes. In addition to being effective for removing suchresidues, stripping and cleaning compositions should also not attack thedifferent metallurgies or insulation layers used in integrated circuitfabrication.

A variety of residue removal compositions and processes suitable forintegrated circuit fabrication have been developed and marketed by EKCTechnology, Inc., the assignee of the present application. Some of thesecompositions and processes are also useful for stripping photoresist,polyimide or other polymeric layers from substrates in integratedcircuit fabrication, and EKC has also developed a variety ofcompositions and processes for stripping such polymeric layers fromsubstrates in integrated circuit fabrication. Such compositions andprocesses are disclosed in the following commonly assigned issuedpatents: U.S. Pat. No. 5,482,566, issued Jan. 9, 1996 to Lee; U.S. Pat.No. 5,399,464, issued Mar. 21, 1995 to Lee; U.S. Pat. No. 5,381,807,issued Jan. 17, 1995 to Lee; U.S. Pat. 5,334,332, issued Aug. 2, 1994 toLee; U.S. Pat. No. 5,279,771, issued January 18, 1994 to Lee; U.S. Pat.No. 4,824,763, issued Apr. 25, 1989 to Lee and U.S. Pat. No. 4,395,348,issued Jul. 26, 1983 to Lee. These compositions have achievedsubstantial success in integrated circuit fabrication applications.However, further development of integrated circuits and theirfabrication processes have created a need for improvement in residueremoval compositions and processes.

As a result of a continuous effort to decrease critical dimension sizein the integrated circuit industry, such as in the fabrication ofsub-micron size devices, etching residue removal and substratecompatibility with chemicals employed in wet processing is becoming moreand more critical for obtaining acceptable yield in very large scaleintegration (VLSI) and ultra large scale integration (ULSI) processes.The composition of such etching residue is generally made up of theetched substrates, underlying substrate, photoresist and etching gases.The substrate compatibility of the wafers with wet chemicals is highlydependent on the processing of the polysilicon, multilevelinterconnection dielectric layers and metallization in thin filmdeposition, etching and post-etch treatment of the wafers, which areoften quite different from one fabrication process to another. Some ofthe above compositions have produced corrosion on certain metalsubstrates, such as those including a titanium metal layer. Titanium hasbecome more widely used in semiconductor manufacturing processes. It isemployed both as a barrier layer to prevent electromigration of certainatoms and as an antireflector layer on top of other metals.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide an improvedcomposition for residue removal and process using such a compositionsuitable for meeting current semiconductor fabrication requirements.

It is another object of the invention to provide such a composition andprocess which is suitable for removing residues from wafers and othersubstrates including one or more titanium metal layers withoutsubstantial attack on such titanium layers.

The attainment of these and related objects may be achieved through useof the residue removal composition and process herein disclosed. Aresidue removal composition in accordance with this invention comprisesa two carbon atom linkage alkanolamine compound, gallic acid orcatechol, optionally, an aqueous hydroxylamine solution, and desirably abalance of water or another suitable polar solvent. A process forremoving a residue from a substrate in accordance with this inventioncomprises contacting the substrate with a composition that contains atwo carbon atom linkage alkanolamine compound for a time and at atemperature sufficient to remove the residue from the substrate.

In practice, we have found that use of a two carbon atom linkagealkanolamine compound gives a residue removing composition that attackstitanium substantially less than prior compositions. At the same time,the two carbon atom linkage alkanolamine compound containing compositiongives equivalent performance as a residue removing composition.

The attainment of the foregoing and related objects, advantages andfeatures of the invention should be more readily apparent to thoseskilled in the art, after review of the following more detaileddescription of the invention, taken together with the drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 are scanning electron microscope (SEM) photographs showingcomparative results achieved using the composition and process of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The two carbon atom linkage alkanolamine compounds suitable for use inthe invention have the structural formula X, ##STR1## wherein X and Yare, independently in each case, hydrogen, methyl or ethyl, and R ishydrogen or an alkyl group containing from 1 to 4 carbon atoms. The twocarbon atom linkage alkanolamine compounds useful in the presentinvention preferably have relatively high boiling points, such as forexample, 75° C. or above. Preferred specific examples of such two carbonatom linkage alkanolamine compounds include monoethanolamine andmonoisopropanolamine.

The composition desirably contains at least about 10% by weight of atleast one two carbon atom linkage alkanolamine compound, from about 5%to about 40% by weight of gallic acid, catechol or other chelatingagent, and optionally, up to about 50 percent by weight of a 50% byweight aqueous hydroxylamine solution. The balance of the composition isdesirably made up of water, preferably high purity deionized water, oranother suitable polar solvent. The solvents can be used singly or asmixtures. The composition preferably includes from about 10% to about80% by weight of at least one two carbon atom linkage alkanolaminecompound, from about 5% to about 30% by weight of the gallic acid orcatechol, from about 10% to about 30% of the hydroxylamine solution,with the remaining balance preferably being water or other suitablepolar solvent.

In practice, it appears that the catechol or gallic acid enhances theability of the two carbon atom linkage alkanolamine compound to removethe residue. At the same time, the presence of the catechol, gallic acidor other chelating agent helps to prevent attack on titanium metallurgy.

Suitable examples of polar solvents for the composition, in addition towater, include dimethyl sulfoxide, ethylene glycol, ethylene glycolalkyl ether, diethylene glycol alkyl ether, triethylene glycol alkylether, propylene glycol, propylene glycol alkyl ether, dimethylsulfoxide, N-substituted pyrrolidone, ethylenediamine andethylenetriamine. Additional polar solvents as known in the art can alsobe used in the composition of the present invention.

The residue cleaning compositions of the present composition areeffective in removing organometallic and metal oxide residue from avariety of integrated circuit silicon wafer substrates, including metallayers, such as aluminum or titanium, oxide layers, such as siliconoxides, nitride layers, such as silicon nitride, and the like. Thecleaning compositions of the present invention are also effective inremoving organometallic and metal oxide residue generated on thesubstrate of etching equipment utilized in the fabrication of integratedcircuits. Examples of commercially available etching equipment includethat available from Lam Research, Tegal, Electrotech, Applied Materials,Tokyo Electron, Hitachi and the like.

The method of cleaning a substrate using the cleaning compositions ofthe present invention involves contacting a substrate havingorganometallic and metal oxide residue thereon with a stripping andcleaning composition of the present invention for a time and at atemperature sufficient to remove the residue. The substrate is generallyimmersed in the stripping and cleaning composition. The time andtemperature are determined based on the particular material beingremoved from a substrate. Generally, the temperature is in the range offrom about ambient or room temperature to about 120° C. and the contacttime is from about 2 to 60 minutes.

The substrate may then be rinsed in a polar solvent, such as isopropylalcohol, followed by a deionized water rinse. The substrate is thenmechanically dried, such as with a spin drier, or nitrogen blow dried.

The following represent non-limiting examples and describe the inventionfurther.

Examples of cleaning compositions according to the present inventionsuitable for removing resist or other organic residues from a substrateare set forth in

                  TABLE 1                                                         ______________________________________                                        Clean-                                                                        ing                                   Additional                              Compo-                                                                              Alkanolamine                                                                             Gallic Acid/                                                                              Hydroxyl-                                                                              Solvent                                 sition                                                                              Wt. %      Catechol Wt. %                                                                            Amine Wt. %                                                                            Wt. %                                   ______________________________________                                        A     60%    DGA     5%   Catechol                                                                             30% (50 Wt %                                                                  Aq. Sol'n)                                   B     55%    MIPA    10%  gallic acid                                                                          30% (50 Wt %                                                                           5% Water                                                             Aq. Sol'n.)                                  C     60%    MEA                 35% (50 Wt %                                                                           5% Water                                                             Aq. Sol'n.)                                  D     60%    MEA     5%   gallic acid                                                                          35% (50 Wt %                                                                  Aq. Sol'n.)                                  E     60%    MIPA    5%   Catechol                                                                             35% (50 Wt %                                                                  Aq. Sol'n.)                                  F     30%    MEA     10%  Catechol                                                                             30% (50 Wt %                                                                           5% Water                                  25%    MIPA                Aq. Sol'n.)                                  G     30%    MEA     10%  gallic acid                                                                          30% (50 Wt %                                                                           5% Water                                  25%    MIPA                Aq. Sol'n.)                                  H     55%    DGA     10%  gallic acid                                                                          30% (50 Wt %                                                                           5% Water                                                             Aq. Sol'n.)                                  ______________________________________                                         Abbreviations:                                                                DGA = diglycolamine                                                           MEA = monoethanolamine                                                   

MIPA=monoisopropanolamine

EXAMPLE 1

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition A at 75° C. for 30minutes to remove process residue from the wafer, for comparativepurposes. FIG. 1 is a scanning electron microscope (SEM) photograph ofthe wafer after this treatment. Substantial undercutting of both Tilayers are visible in this photograph.

EXAMPLE 2

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition B at 75° C. for 30minutes to remove process residue from the wafer. FIG. 2 is a SEMphotograph of the wafer after this treatment. No undercutting of thelower Ti layer is visible, and a slight undercutting of the upper Tilayer is visible.

EXAMPLE 3

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition C at 75° C. for 30minutes to remove process residue from the wafer, as a control. FIG. 3is a SEM photograph of the wafer after this treatment. Undercutting ofboth Ti layers is visible.

EXAMPLE 4

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition D at 75° C. for 30minutes to remove process residue from the wafer. FIG. 4 is a SEMphotograph of the wafer after this treatment. A slight undercutting ofthe lower Ti layer is visible, and no undercutting of the upper Ti layeris visible.

EXAMPLE 5

A semiconductor wafer having a patterned metal stack consisting ofW/Ti/SiO₂ was treated with composition E at 75° C. for 30 minutes toremove process residue from the wafer. FIG. 5 is a SEM photograph of thewafer after this treatment. No undercutting of the Ti layer is visible.

EXAMPLE 6

A semiconductor wafer having a patterned metal stack consisting ofTiN/Ti/Al/Ti/TiN/BPSG (boron phosphosilicate glass) was treated withcomposition F at 75° C. for 30 minutes to remove process residue fromthe wafer. FIG. 6 is a SEM photograph of the wafer after this treatment.No undercutting of the Ti layers is visible.

EXAMPLE 7

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition G at 75° C. for 30minutes to remove process residue from the wafer. FIG. 7 is a SEMphotograph of the wafer after this treatment. No undercutting of the Tilayers is visible.

EXAMPLE 8

A semiconductor wafer having a patterned metal stack consisting ofTiN/Al/Ti/TiN/Ti/SiO₂ was treated with composition H at 75° C. for 30minutes to remove process residue from the wafer, for comparativepurposes. FIG. 8 is SEM photograph of the wafer after this treatment.Undercutting of the Ti layers is visible.

The above examples show that compositions B, D, E, F and G successfullyremove residues from substrates having a titanium metallurgy whilereducing or eliminating attack on the titanium metallurgy. Increasedamounts of catechol or gallic acid produce an improved reduction ofattack on the titanium metallurgy. The comparative compositions A, C andH all show substantial attack on the titanium metallurgy, even when atwo carbon atom linkage alkanolamine compound is used in the absence ofgallic acid or catechol. When gallic acid or catechol is used with analkanolamine compound other than a two carbon atom linkage alkanolaminecompound, the gallic acid or catechol does not show a similar reductionof attack of the composition on the titanium metallurgy.

It should now be readily apparent to those skilled in the art that anovel composition and process capable of achieving the stated objects ofthe invention has been provided. The improved two carbon atom linkagealkanolamine compound based composition and process using such acomposition of this invention is suitable for meeting currentsemiconductor fabrication requirements. The composition and process issuitable for removing photoresist residues and other residues fromwafers and other substrates including one or more titanium metal layerswithout substantial attack on such titanium layers.

It should further be apparent to those skilled in the art that variouschanges in form and details of the invention as shown and described maybe made. It is intended that such changes be included within the spiritand scope of the claims appended hereto.

What is claimed is:
 1. A composition for removal of process residue froma substrate having at least one layer consisting essentially oftitanium, a titanium alloy or a titanium compound, which comprises:(a) amonoethanolamine or monoisopropanolamine two carbon atom linkagealkanolamine compound, (b) a chelating agent, wherein the chelatingagent is gallic acid or catechol, and (c) an aqueous hydroxylaminesolution.
 2. The composition of claim 1 additionally comprising:water ora polar organic solvent.
 3. The composition of claim 2 in which thepolar organic solvent comprises ethylene glycol, ethylene glycol alkylether, diethylene glycol alkyl ether, triethylene glycol alkyl ether,propylene glycol, propylene glycol alkyl ether, N-substitutedpyrrolidone, ethylenediamine or ethylenetriamine.
 4. The composition ofclaim 1 in which the two carbon atom linkage alkanolamine compound ispresent in an amount of at least about 10 percent by weight.
 5. Thecomposition of claim 1 in which the gallic acid or catechol is presentin an amount of from about 5 percent to 30 percent by weight.
 6. Thecomposition of claim 5in which the composition contains from about 5 to50 percent by weight of the aqueous hydroxylamine solution.
 7. Thecomposition of claim 4 in which the two carbon atom linkage alkanolaminecompound is present in an amount of from about 10 percent by weight to80 percent by weight.
 8. The composition of claim 7 in which thechelating agent is gallic acid or catechol and is present in an amountof from about 5 percent to 30 percent by weight.